FIG. 2.

Effect of the PA4352 knockout in P. aeruginosa on recovery from nitrate starvation in the anaerobic stationary phase. Cultures of P. aeruginosa were incubated anaerobically in LB supplemented with 50 mM KNO₃ and allowed to pass 9 h of stationary phase before being diluted in fresh LB medium. The inoculum contained 4.2 × 10⁸ to 6.1 × 10⁸ viable cells per ml as determined by viable-cell counts and Live/Dead staining (see Materials and Methods). The diluted cultures were incubated aerobically at 37°C to generate the growth curves shown of the wild-type strain containing the empty mini-CTX2 (NB058) (open triangles), the ΔPA4352 mutant containing the empty mini-CTX2 vector (NB059) (filled squares), and the complemented ΔPA4352 mutant (NB060) containing pNB011 with the PA4352 gene (open squares). To rescue the phenotype of the ΔPA4352 mutant, one culture of the ΔPA4352 mutant was supplemented with additional KNO₃ (30 mM) 5 hours prior to dilution (filled circles).